Check the consumer rights in your country. Apple may legally obligated to repair the device for free. Because of the consumer rights in my country (United Kingdom), Apple had to cover the costs of the repair. If this applies to you, waive your consumer rights in the store or make a claim by contacting Apple here: https://support.apple.com/en-gb/HT201232 .
For those who consumer law does not apply to, it may not necessarily mean you have to replace the screen. When in the store, the Apple worker informed me of the prices if I had to pay. He said that the price for the cable (around £100) and the price for the screen (around £300) were separate costs. And I could have the cable replaced without replacing the screen, reducing the cost. They even showed me the Apple Store email confirming the two separate prices. So it may only end up costing £100 not £500. Arguably still a high price for a cable, but a lower price than originally quoted.
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EDIT: This cable that the Apple store said they could replace for £100 turned out to be the wrong cable and the one which either supplies power to the screen or transmits information (not sure which one) but it did not fix the issue. They said it would be a £500 screen replacement.
Check the consumer rights in your country. Apple may legally obligated to repair the device for free. Because of the consumer rights in my country (United Kingdom), Apple had to cover the costs of the repair. If this applies to you, waive your consumer rights in the store or make a claim by contacting Apple here: https://support.apple.com/en-gb/HT201232 .
For those who consumer law does not apply to, it may not necessarily mean you have to replace the screen. When in the store, the Apple worker informed me of the prices if I had to pay. He said that the price for the cable (around £100) and the price for the screen (around £300) were separate costs. And I could have the cable replaced without replacing the screen, reducing the cost. They even showed me the Apple Store email confirming the two separate prices. So it may only end up costing £100 not £500. Arguably still a high price for a cable, but a lower price than originally quoted.